How to remove unintentional distortion from geometry?
So, this turned out to be much easier than I anticipated. It is all about flipped normals where some faces have their normal vectors pointing inside the mesh instead of outside. It can be shown in Edit mode (face mode) with face dots and face orientation enabled in the Overlays like this:

It turns out all you need to do is select all the faces on the mesh and recalculate the normals (you want blue facing outward; blue is facing toward you and red is facing away from you). Another way to see the direction of the face normals (instead of turning on Face Orientation) is by showing their vectors:

Big thanks to Chris Kohl (ckhol_art) over at https://blenderartists.org/t/how-to-remove-unintentional-distortion-from-geometry/1241104/3 for providing me with this fantastic answer and explanation.